The railways industry is under constant pressure to maintain lower costs and also to increase the safety of rail travel. Any accident can be costly in terms of human life and repair costs and is inevitably scrutinised publicly to determine the cause.
One aspect which is obviously of fundamental importance is the rail on which the trains run. Over the years in which the railways have operated, improvements have been made in the materials and the design of rails to ensure that they are able to withstand large stresses and also the weathering to which they are exposed.
A rail track comprises a series of individual rails, joined together—for example by welding and/or bridging elements to form a continuous length. The rails are usually formed from high quality premium steel for strength and durability. Support for the rails is provided by high quality ballast materials and sleepers laid perpendicularly to the direction of travel.
The joints between rails however remain sources of potential weakness and are frequently the parts of a track most likely to weaken or fail. The usual method of holding two rails together in a joint is to fasten the rails together using what is termed in the art as a fishplate.
Where a defect arises, or as a preventative measure, for example where a section of track is broken apart or cracked, a clamp can be fastened about the fishplate to hold this and the rails together. Moreover, the clamps themselves are subject to the same stress forces. Replacement of defective and worn rail is costly as this has to be carried out when no trains are using the track.
Additionally, it is important to be able to determine the stress to which a joint is being subjected. This is likely to become more of an issue in the future as the use of the railways expands and trains using a particular stretch of rail become more frequent, faster and also heavier. Also a change over time of readings taken can indicate wear and tear, or even wilful damage to the track or clamp. Means are therefore utilised to determine where problems are likely to occur and so prevent them happening.
Measuring devices are therefore often employed to measure the forces and rail movement experienced by the rail joint. Such forces are dependent on the rail temperature, the speed of a train, the train's mass and also the location of the track. In addition, the stress on a rail section on a curve of the track will differ considerably to that for a section on straight track. Ideally, the device measures the forces in a non-invasive fashion so that taking of the measurements does not itself cause weakening.
Preferably, any measuring device is able to operate without the constant requirement for supervision by an operator and also to transmit measurements to a remote data collector for analysis, thus obviating the need for regular retrieval of information from the device. In addition, the device needs to be able to operate in the open, and so needs to be resistant to weathering.
It is an object of the present invention to provide a clamp which addresses the above problems. It is a further object of the invention to provide a damp which facilitates and improves the measurement of the forces and conditions experienced by a railway rail and/or joint between rails.